1. Field of the Invention
The present invention relates to an infrared communication control apparatus and method for handling a plurality of infrared communication schemes at the same time, in the case of data communication using infrared signals.
2. Description of the Related Art
Japanese Unexamined Patent Publication JP-A 8-195785 (1996), for example, discloses an infrared communication control apparatus for infrared communication systems having a plurality of infrared modulation/demodulation schemes, the infrared communication control apparatus being capable of generating a proper type of infrared signal by automatically judging what type of infrared signal is actually received. The configuration of this prior art control apparatus is shown in FIG. 10 in a simplified fashion. An application program conducts data communication through a communication port controller 1. The data input to the communication port controller 1 is modulated into infrared signals by an infrared modem 2 or received infrared signals are demodulated into data by the infrared modem, and then they are given to the application program through the communication port controller 1. The type of the received infrared signals is automatically detected by an infrared modulation/demodulation scheme automatic detector 3. Reception and transmission of the infrared signals are carried out by an infrared unit 4. The infrared modem 2 and the infrared modem modulation/demodulation automatic detector 3 are included in an infrared controller 5 for controlling the infrared unit 4. The infrared unit 4 includes a light-emitting diode for generating an infrared ray and a photodiode or photo-transistor for receiving light.
Conventionally, an application program is required to switch an infrared modulation/demodulation scheme to an infrared modulation/demodulation scheme employed by the other party before conducting data communication by infrared rays. The user of an infrared communication control apparatus, therefore, is required to recognize the infrared modulation/demodulation scheme employed by the unit of the other party beforehand. In the prior art disclosed in JP-A 8-195785, the infrared signals received from the other party are detected by using the infrared modulation/demodulation scheme automatic detector 3 and the type of the infrared signals is classified, so that the infrared modulation/demodulation scheme is automatically detected. The application program, therefore, can conduct data communication through a communication port regardless of the infrared modulation/demodulation scheme of the other party or a protocol of the infrared signals.
An infrared communication scheme used for a remote controller of a domestic electric appliance such as a TV set can be cited as one of the most successful examples. As a personal computer has become widespread, an infrared modulation/demodulation scheme based on digital communication by a computer system has also come to be employed recently. An example of the infrared modulation/demodulation scheme using digital data as a medium for digital communication is an ASK scheme proposed by Sharp Kabushiki Kaisha. The ASK (amplitude shift keying) scheme is used for transmitting personal information registered in an electronic notebook or the like, to a personal computer. An IrDA scheme defined by an IrDA (Infrared Data Association) Committee established to support the infrared communication between products of different manufacturers is another example. Still another infrared communication scheme defined by the IrDA Committee is a consumer IR scheme for an intelligent remote controller of interactive type intended for domestic use. As described above, various infrared modulation/demodulation schemes are currently used. An application program, therefore, is required to switch an infrared modulation/demodulation scheme to an infrared modulation/demodulation scheme employed by a communication unit of the other party before conducting data communication using an infrared unit. As a result, the user is required to consider the infrared modulation/demodulation scheme of the communication unit of the other party, and unless an infrared modulation/demodulation scheme employed by the user suits that of the communication unit of the other party, the user is unable to conduct data communication. Furthermore, various arrangements for data communication constituting communication rules exist as a unique communication protocol for each infrared modulation/demodulation scheme. It is therefore necessary to switch the communication protocol as well as the infrared modulation/demodulation scheme.
In the prior art disclosed in JP-A 8-195785, the infrared modulation/demodulation scheme can be automatically detected only after the infrared signals are received from the infrared communication unit of the other party. In the case of communication with a passive infrared communication unit which begins transmission only after receiving infrared signals from an infrared unit of the other party, the infrared communication scheme may not be determined automatically. Many of the existing infrared peripheral units employ such a passive scheme. Even a computer system having a function of automatically detecting the infrared communication scheme is required to transmit ahead an infrared signal when transmitting data to an infrared peripheral unit performing passive infrared communication. In addition, it is difficult to switch a control conforming to each infrared communication scheme. The result is so contradictory that even in a case where a plurality of infrared communication schemes can be switched over, the infrared communication scheme to be used for first transmission cannot be determined. Consequently, the prior art disclosed in JP-A 8-195785 cannot realize smooth data communication with the passive infrared communication unit often used in the existing infrared peripheral units.